Venetian blinds consist of a plurality of horizontal slats. These slats rest on ladders made of cord, fabric tape, or flexible sheets of sheer material. Blinds have a headrail and bottomrail, the bottomrail being either one solid rail or two parallel rails connected by a cord. The blinds have a lift cord or cords, traditionally connected from the bottomrail through route holes in the slats, to a lift mechanism or cord lock in the headrail. In some venetian blinds the lift cords are placed proximate to the front and rear edges of the slats, and tiny notches or slots are made in the slats for the lift cords to pass through from the bottomrail into the headrail. Blinds are raised to stack slats at the top by pulling the lift cords through a cord lock, which locks into place by pulling the lift cords laterally to catch the lock and then back to set the lock. Alternatively, an axle driven cord collection system may be used for one or more sets of lift cords in place of a cord lock. In this type of blind, as in most venetian blinds, when the blind is lowered all of the slats can be in an open, horizontal position, or in a closed tilted position or some intermediate position. The blind cannot have one portion that is open and another portion which is closed unless the owner turns the slats individually. Yet, there has been a demand for other types of window coverings in which the upper half of the window is uncovered while the lower half of the window is covered. This feature allows the consumer to look out the top of the window with a clear view to the outside without having intense sunlight on the furniture and people that are ordinarily adjacent the lower half of the window. It also affords privacy to the people inside the building wherever ground level is lower than the window.
One type of blind which has been offered to meet this demand is the so-called bottom-up blind. In this type of blind the slats are stacked on the bottomrail, which typically rests adjacent the sill and has lift cords which run up to the headrail. A moving rail is placed on top of the slats and is connected to lift cords which run through the headrail. Pulling the lift cords raises moving rail and the slats from the bottomrail. Examples of this type of blind are disclosed in U.S. Pat. Nos. 7408 to Bohrer, 12,695 to Rose, 2,223,640 to Kwon and U.S. Pat. No. 5,443,108. to Levert et al. These blinds tend to be very bulky and can be awkward to operate because the moving rail is constantly changing position relative to the operator. Also, the two sets of lift cords are confusing. None of these blinds allows some of the slats to be in an open horizontal position while other slats are in a closed tilted position.
Laborda et al. in U.S. Pat. Nos. 2,116,356, Graham in 2,719,856 and Ewing in 2,427,266 disclose blinds in which the lower set of slats can be titled to a position different from the upper set of slats. All of these blinds have full length ladders that extend from the headrail to the bottomrail. Tilt cords are attached to the rear rails of the ladders at a point between the headrail and the bottomrail. Pulling the tilt cords moves the lower portion of the rear ladder rails relative to the front ladder rails tilting the lower slats. These blinds are more expensive to make and the additional tilt cords attached to the ladder rail detract from the appearance of the blind and require a means in the headrail and descending to the operator to tilt the lower portion. Again, the double headrail controls are often confusing and the lower slats are limited in the angles that they can be tilted. Finally, titling these blinds can actually shorten their length which compromises the desired features of privacy. Consequently, there is a need for a venetian blind which has separately tilting slat sections, but does not require additional cords and/or controls. Ideally, this blind will require a minimum of additional hardware and have the appearance of an ordinary blind. Also the blind should be able to utilize cord ladders, fabric tape ladders, or sheer material sheet ladders. Overall, there is still a need for an easily operated, neat-looking venetian type blind with several cording style options wherein the upper slats can be open while the lower slats are closed, or vice-versa, or some intermediate combination.